Method and apparatus for performing blank detection on an optical storage disc

ABSTRACT

A method for performing blank detection on an optical storage disc includes receiving information read by an optical storage device from the optical storage disc, and checking corresponding data of the information to operate blank detection.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application and claims the benefit ofU.S. application Ser. No. 10/905,428, filed on Jan. 4, 2005, now U.S.Pat. No. 7,349,312.

BACKGROUND

The present invention relates to optical storage devices, and moreparticularly, to a method and an apparatus for performing blankdetection involved with Error Correction Code (ECC) decoding ofinformation read from an optical storage disc.

Digital Versatile Discs (DVDs) and DVD drives are typical of the opticalstorage discs and optical storage devices, respectively. When the dataflow generated by the optical storage device while reading the opticalstorage disc is interrupted, the decoder for decoding the data flow isnot able to output a proper decoded signal. For example, the decoder fordecoding the data flow will output a blank signal. A method for solvingthe data flow interruption problem mentioned above is to perform blankdetection on the optical storage disc to control the decoder's decodingaction on the data flow according to detection results of the blankdetection. In this way, the decoder neither stops outputting signals noroutputs blank signals.

According to the blank detection method of the related art, when aprocessing unit of a front stage in the optical storage device detectsthe interruption of the data flow during a reading process, an opticalpickup module of the optical storage device will be returned to anearlier location corresponding to data that has already been read butnot yet buffered. That is, the optical storage device must reread andbuffer the data that has not been buffered for further decoding. As thecontrol of the blank detection mentioned above, the reading action ofthe optical pickup module, and the buffering control of the data flowcorrespond to independent control processes respectively, the opticalstorage device has to firstly perform the reading action of the opticalpickup module, secondly perform the blank detection, then perform thereading action of the optical pickup module again, and finally performthe buffering control mentioned above.

As a result of the blank detection method of the related art, althoughthe data flow interruption problem mentioned above is solved, a newproblem of repeating the reading action of the optical pickup module isintroduced. The optical storage device has to waste time moving theoptical pickup module around the same region of the optical storage discand rereading the same data stored in that region. An improved blankdetection method is therefore required so that the performance of theoptical storage device may be enhanced.

SUMMARY

The present invention provides a method for performing blank detectionon an optical storage disc. The method comprises: receiving informationread by an optical storage device from the optical storage disc; andchecking corresponding data of the information to operate blankdetection.

Accordingly, the present invention further provides a circuit forperforming blank detection on an optical storage disc. The circuitcomprises: a buffering module for receiving information read by anoptical storage device from the optical storage disc; and a checkingmodule electrically connected to the buffering module for checkingcorresponding data of the information to operate blank detection.

These and other objectives of the present invention will no doubt becomeobvious to those of ordinary skill in the art after reading thefollowing detailed description of the preferred embodiment that isillustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart of a method for performing blank detection on anoptical storage disc according to a preferred embodiment of the presentinvention.

FIG. 2 is a block diagram of a circuit for performing the blankdetection on the optical storage disc according to the preferredembodiment of the present invention.

FIG. 3 is a data structure diagram of buffered data stored in the memoryshown in FIG. 2.

FIG. 4 is a data structure diagram of the data flow of the buffered datashown in FIG. 2.

DETAILED DESCRIPTION

Please refer to FIG. 1 and FIG. 2. FIG. 1 is a flowchart of a method forperforming blank detection on an optical storage disc 102 according to apreferred embodiment of the present invention, and FIG. 2 is a blockdiagram of a circuit 201 for performing the blank detection on theoptical storage disc 102 according to the preferred embodiment of thepresent invention. The circuit 201, also referred to as the blankdetection circuit 201, is installed in an optical storage device 200 asillustrated in FIG. 2. The optical storage device 200 includes amicroprocessor unit (MPU) 104, an Error Correction Code (ECC) blockcontroller 106, an ECC decoder 108, an optical pickup module 110, and afront stage circuit 112. In addition, the blank detection circuit 201includes a buffering module 201 a and a checking module 201 b. Thebuffering module 201 a is capable of buffering storage managementinformation 103 read by the optical pickup module 110 from the opticalstorage disc 102 to generate buffered data 252. The checking module 201b is electrically connected to the buffering module 201 a and is usedfor checking corresponding data of an ECC block in the buffered data 252to determine if the ECC block is a blank ECC block. According to thisembodiment, the optical storage disc 102 and the optical storage device200 are a Digital Versatile Disc (DVD) and a DVD drive, respectively. Inaddition, the storage management information 103 represents datarecording states of the optical storage disc 102. If the optical storagedisc 102 complies with the DVD-R/RW specification, the storagemanagement information 103 can be the information of the RecordingManagement Data (RMD). If the optical storage disc 102 complies with theDVD+R specification, the storage management information 103 can be theinformation of the Table of Content (TOC)/Disc Control Block (DCB).

The buffering module 201 a includes a demodulator 202 coupled to theoptical pickup module 110 for demodulating the data flow of the buffereddata 252; a buffer controller 204 electrically connected to thedemodulator 202 for controlling the data flow of the buffered data 252;a target search unit 206 electrically connected to the demodulator 202for generating a logical address search signal 258 according to thebuffered data 252 to control the buffer controller 204; an OR logic gate208 electrically connected to the target search unit 206, the buffercontroller 204, and the front stage circuit 112 for controlling thebuffer controller 204 according to a physical address search signal 256generated by the front stage circuit 112 and the logical address searchsignal 258; and a memory 210 electrically connected to the buffercontroller 204 for storing the buffered data 252. The buffering module201 a is capable of seeking locations within the buffered data 252according to the physical address search signal 256 and the logicaladdress search signal 258.

The checking module 201 b includes an AND logic gate 222 electricallyconnected to the demodulator 202 and the front stage circuit 112 forderiving blank header information 262 from a sync signal 254 outputtedby the demodulator 202 according to a blank signal 260 generated by thefront stage circuit 112; a threshold storage unit 226 coupled to the MPU104 for storing two predetermined thresholds 264 and 266; a blank sectordetection unit 224 electrically connected to the AND logic gate 222, thethreshold storage unit 226, and the memory 210 for determining if asector in the buffered data 252 is a blank sector according to the blankheader information 262 derived by the AND logic gate 222 and thepredetermined threshold 264, and generating at least one blank sectordetection record 265 correspondingly; and a blank ECC block detectionunit 228 electrically connected to the threshold storage unit 226 andthe MPU 104 and coupled to the memory 210 through the ECC blockcontroller 106 and the ECC decoder 108 for determining if an ECC blockis a blank ECC block according to the blank sector detection record 265and the predetermined threshold 266 during the decoding process of thedecoder 108. As illustrated in FIG. 2, the blank sector detection unit224 stores the blank sector detection record 265 in the memory 210, andthe blank ECC block detection unit 228 derives the blank sectordetection record 265 from the memory 210. When a detection result of theblank ECC block detection unit 228 indicates that the ECC block is ablank ECC block, the blank ECC block detection unit 228 outputs aninterruption signal 268 to the MPU 104 to complete the detection processof the present invention method. This detection process is referred toherein as the blank detection method. Please note that the order of thefollowing steps is not a limitation to the present invention method. Thedetection process is as follows:

-   Step 10: Buffer the storage management information 103 read by the    optical storage device 200 from the optical storage disc 102 using    the buffering module 201 a to generate the buffered data 252. Each    ECC block E-0, E-1, . . . , E-N of the buffered data 252 includes    sixteen sectors S-0, S-1, . . . , and S-15, and each sector S-0,    S-1, . . . , S-15 includes thirteen frames F-0, F-1, . . . , and    F-12. In addition, the frames F-0, F-1, . . . , and F-12 shown in    FIG. 3 correspond to sync frame sets SF-0, SF-1, . . . , and SF-12    shown in FIG. 4, respectively. Wherein each sync frame set SF-I    (I=0, 1, . . . , 12) out of the sync frame sets SF-0, SF-1, . . . ,    and SF-12 includes two sync frames SF-I-0 and SF-I-1 in the data    flow of the buffered data 252. In contrast to the data format of the    data flow of the buffered data 252, the data format in the memory    210 further includes two additional regions. As illustrated in FIG.    3, the two additional regions include the reserved region F-13 r and    the blank region F-13 b. Both the reserved region F-13 r and the    blank region F-13 b illustrated in FIG. 3 are appended to the end of    the frame F-12 when the data flow of the buffered data 252 is stored    in the memory 210. When the data flow of the buffered data 252 is    interrupted, the optical storage device 200 is capable of generating    blank sync headers SY0′, SY1′, . . . , and SY7′ according to a    physical wobble signal of the optical storage disc 102 so that the    data flow of the blank sync headers SY0′, SY1′, . . . , and SY7′ and    the data flow of the storage management information 103 form the    buffered data 252 that is continuously arranged. Similar to normal    sync headers SY0, SY1, . . . , and SY7 illustrated in FIG. 4, the    blank sync headers SY0′, SY1′, . . . and SY7′ are used for    identifying the relative locations of the sync frames SF-I-0, SF-I-1    (I=0, 1, . . . 12) with respect to the sector 400 that the sync    frames SF-I-0 and SF-I-1 belong to.-   Step 20: Identify a sync frame SF-I-J (I=0, 1, . . . , 12, and    J=0, 1) needing to be identified in the sync signal 254 as a normal    sync frame or a blank sync frame according to whether the sync    header of the sync frame SF-I-J is one of the normal sync headers    SY0, SY1, . . . , and SY7 or one of the blank sync headers SY0′,    SY1′, . . . , and SY7′. More specifically, when the sync header of    the sync frame SF-I-J is one of the blank sync headers SY0′, SY1′, .    . . , and SY7′, the sync frame SF-I-J is a blank sync frame.    According to this embodiment, this step is implemented by using the    AND logic gate 222 to derive the blank header information 262 from    the sync signal 254 outputted by the demodulator 202 according to    the blank signal 260.-   Step 30: Determine if the sector 400 is a blank sector according to    the number of the blank sync frame(s) in the sector 400 using the    blank sector detection unit 224. The blank sector detection record    265 corresponding to the sector 400 is recorded in the blank region    F-13 b. When the number of the blank sync frame(s) is greater than    the predetermined threshold 264, the sector 400 is determined to be    a blank sector.-   Step 40: Determine if the ECC block under consideration is a blank    ECC block according to the number of the blank sector(s) in the ECC    block using the blank ECC block detection unit 228. The blank sector    detection record 265 corresponding to a sector in the ECC block    indicates whether the sector is a blank sector. When the number of    the blank sector(s) in the ECC block is greater than the    predetermined threshold 266, the ECC block is determined to be a    blank ECC block.

The predetermined thresholds 264 and 266 respectively utilized in Step30 and Step 40 can be derived from experiments or trial tests.Additionally, both of the predetermined thresholds 264 and 266 can beadjusted by the MPU 104 using at least one MPU command, and thethreshold storage unit 226 can be a register or a storage component thatexists in the optical storage device 200. The existing register orstorage component used as the threshold storage unit 226 is only animplementation choice and is not meant as a limitation to the presentinvention. According to another embodiment of the present invention,while both of the predetermined thresholds 264 and 266 are adjustablevalues, the predetermined thresholds 264 and 266 can be stored in theblank sector detection unit 224 and the blank ECC block detection unit228, respectively. According to another embodiment of the presentinvention, the predetermined thresholds 264 and 266 can be fixed valuesstored in the blank sector detection unit 224 and the blank ECC blockdetection unit 228, respectively. According to yet another embodiment ofthe present invention, the blank sector detection unit 224 used in step20 is capable of directly identifying the sync frame SF-I-J needing tobe identified in the sync signal 254 as a normal sync frame or a blanksync frame according to whether the sync header of the sync frame SF-I-Jis one of the normal sync headers SY0, SY1, . . . , and SY7 or one ofthe blank sync headers SY0′, SY1′, . . . , and SY7′. That is, the blanksector detection unit 224 of this embodiment may directly identify thenormal sync headers SY0, SY1, . . . , and SY7 and the blank sync headersSY0′, SY1′, . . . , and SY7′.

It is an advantage of the present invention that when the blankdetection of the optical storage disc is completed, the buffered datacan be used as the data needed during error correction that will beperformed according to error correction codes or used as the data neededfor further decoding. Therefore, the present invention method andapparatus do not need to repeatedly perform the read action of theoptical pickup module in the optical storage device. That is, duringoperations of the optical storage device, the blank detection and thebuffering control are merged into one process to be performed togetherso that there is no need for extra movement and read action of theoptical pickup module.

It is another advantage of the present invention that the firstinformation can be the storage management information representing datarecording states of the optical storage disc of the optical storagedisc. Therefore, the speed of the blank detection can be increased.Those skilled in the art will readily observe that numerousmodifications and alterations of the device and method may be made whileretaining the teachings of the invention. Accordingly, the abovedisclosure should be construed as limited only by the metes and boundsof the appended claims.

1. A method for performing blank detection on an optical storage disc,the method comprising: (a) receiving first information read by anoptical storage device from the optical storage disc, wherein when thereceiving step is interrupted, the optical storage device is capable ofgenerating second information according to track information of theoptical storage disc so that the second information and the firstinformation read by the optical storage device from the optical storagedisc is continuously arranged; and (b) checking corresponding data ofthe received first information to operate blank detection fordetermining the first received information as blank data.
 2. The methodof claim 1, wherein the first information comprises storage managementinformation of the optical storage disc, and the storage managementinformation represents data recording states of the optical storagedisc.
 3. The method of claim 2, wherein the optical storage disc is aBlu-Ray Disc (BD), and the first information is Disc Management Area(DMA) information or Temporary Disc Management Area (TDMA) information.4. The method of claim 2, wherein the optical storage disc is a HighDefinition Digital Versatile Disc (HD DVD), and the first information isRecording Management Zone (RMZ) information or Lead-In RMZ (L-RMZ)information.
 5. The method of claim 1, wherein step (b) furthercomprises determining if an Error Correction Code (ECC) block derivedfrom the first information is a blank ECC block according to the secondinformation.
 6. The method of claim 5, wherein the track information isa physical wobble signal of the optical storage disc.
 7. The method ofclaim 5, wherein each ECC block includes at least one sector, eachsector includes a plurality of sync frames, each sync frame includes async header for identifying the relative location of the sync frame withrespect to the sector that the sync frame belong to, and step (b)further comprises: (b-1) identifying a first sync frame of the at leastone sector as a normal sync frame or a blank sync frame according towhether the sync header of the first sync frame is a first sync headercorresponding to the first information or a second sync headercorresponding to the second information, respectively, wherein when thesync header of the first sync frame is a second sync header, the firstsync frame is a blank sync frame; (b-2) determining if the at least onesector is a blank sector according to the number of the blank syncframes in the at least one sector, wherein when the number of the blanksync frames is greater than a first predetermined threshold, the atleast one sector is a blank sector; and (b-3) determining if the ECCblock is a blank ECC block according to the number of the blank sectorsin the ECC block.
 8. The method of claim 7, further comprising:adjusting the first predetermined threshold.
 9. The method of claim 7,wherein each ECC block includes a plurality of sectors, and step (b-3)further comprises determining that the ECC block is a blank ECC blockwhen the number of the blank sectors in the ECC block is greater than asecond predetermined threshold.
 10. The method of claim 1, furthercomprising: seeking locations within the information according to atleast one seeking signal.